Optimized Design Of LoRaWAN Network Server For Smart Municipal Applications

LoRa(Long Range)network server(Network Server,NS)is a component that implements the LoRaWAN(Long Range Wide-Area Net Work)protocol function.It is responsible for the management of LoRa terminals and LoRa base stations,and realizes that LoRa messages are in the terminal and Transfer between application servers.In the smart municipal scene,although LoRaWAN has excellent performance in terms of long-distance coverage and low power consumption,it still has room for improvement in data transmission efficiency.Therefore,this article focuses on the data transmission problem of LoRaWAN in the municipal scene application process.The current LoRaWAN NS implementation proposes several optimization methods:1.Proposed a fragmentation scheme applied to the LoRaWAN protocol layer.Aiming at the problem of LoRaWAN’s insufficient support for long message transmission due to chip reasons,the solution proposes to optionally carry an information field in the header of the message,which is used to negotiate whether to allow fragmented transmission between the terminal and the NS.The slice header only occupies one byte of overhead,which is a slicing scheme with compatibility and low overhead.Through theoretical analysis and modeling verification of fragmentation efficiency,the results show that due to the smaller fragmented message length,the collision probability is reduced to a certain extent.The fragmentation scheme is used in a network where terminals are densely deployed,and fragmentation is optimally configured.In the case of the number,the data extraction rate using this fragmentation scheme is 2.9 times that of the current non-fragmentation mode.2.Proposed a dynamic adaptive rate scheme that equalizes the uplink and downlink signal-to-noise ratio.Based on the asymmetry of the uplink and downlink signal reception strength between the terminal and the base station,and the poor performance of the original algorithm in the channel change scenario,a method that takes into account the uplink and downlink signal-to-noise ratio and can linearly adjust the evaluation based on the current channel conditions is proposed.The algorithm of the parameter.Tests have verified that the improved algorithm has increased the data extraction rate by 14% compared to the original algorithm in small and medium-sized network scenarios where the channel noise fluctuates greatly.At the same time,the test results of constructing the uplink and downlink signal strength asymmetric model indicate that When the intensity difference is 5d B,when the terminal position is within the coverage of the spreading factor 7,the improved algorithm can reduce the retransmission rate by 44% compared with the current algorithm,and the terminal in other positions also has different degrees of improvement.3.A load-balanced downlink path selection algorithm is proposed.Based on the problem of how NS selects the appropriate downlink path in the dense deployment scenario of multiple LoRa base stations overlapping coverage,a load balancing path selection algorithm that delimits a safe interval for the downlink impact factor is proposed.The experimental results show that in the scenario of uneven terminal deployment,the data delivery rate of the improved algorithm is about 5% higher than that of the original algorithm.Among them,compared with the signal priority algorithm,a more balanced downlink load rate is achieved;compared with the weighted average algorithm,it can help the remote terminal to better balance the signal and load factors,and reduce the probability of downlink packet loss caused by the asymmetry of the uplink and downlink channels.